The answer sheet says, "O2 has less complex structure and therefore fewer degrees of freedom therefore less disorder".

Do you think my answer is right too?

(Original post by charco)
You just need to hone your answer to include the complexity of carbon dioxide to include the different bends and stretches possible in the molecular vibration, i.e. degrees of freedom.

CO2 has 2 stretching modes, asymmetric and symmetric. It also has bending modes unlike O2.

(Original post by JMaydom)
CO2 has 2 stretching modes, asymmetric and symmetric. It also has bending modes unlike O2.

Beyond just looking at how many atoms are in the molecule (more atoms -> more degrees of freedom -> greater absolute entropy) is there any way of telling which one has more "modes" and thus higher entropy (ignoring the other factors that affect SO)? The name, perhaps, of the theories behind this field would be appreciated

(Original post by Big-Daddy)
Beyond just looking at how many atoms are in the molecule (more atoms -> more degrees of freedom -> greater absolute entropy) is there any way of telling which one has more "modes" and thus higher entropy (ignoring the other factors that affect SO)? The name, perhaps, of the theories behind this field would be appreciated

(Original post by Big-Daddy)
Beyond just looking at how many atoms are in the molecule (more atoms -> more degrees of freedom -> greater absolute entropy) is there any way of telling which one has more "modes" and thus higher entropy (ignoring the other factors that affect SO)? The name, perhaps, of the theories behind this field would be appreciated

Group theory, a branch of maths applied to chem. I don't understand it, I only know how to apply it.

One important rule is that N# of vibrational modes = 3N-6 with N the number of atoms in the molecule. This is slightly altered to 3N-5 for Linear molecules.

(Original post by Big-Daddy)
Beyond just looking at how many atoms are in the molecule (more atoms -> more degrees of freedom -> greater absolute entropy) is there any way of telling which one has more "modes" and thus higher entropy (ignoring the other factors that affect SO)? The name, perhaps, of the theories behind this field would be appreciated